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SB 14-01-31 Horizontal Stabilizer Cracks - Worth the work?

pecanflyboy

Well Known Member
The short of the long story is that I have a newly built RV-7 horizontal stabilizer and elevator that I'm about to take to paint, and then install on my flying aircraft. I installed the doublers for the elevator spar cracks per SB 14-02-05, which was easy.

I have the kit for SB 14-01-31 to permanently comply with the service bulletin for the horizontal stabilizer cracks. It is a bigger job then I thought.

Is it worth all the work to install this kit on the horizontal stabilizer? Obviously, it is a good time as it is off the airplane and has yet to be painted.

$
 
I did it more for my own piece of mind. It was a bit of work, but after so many years without doing real metal fabrication while doing the engine and panel, it was nice to get in there and drill out and drive some rivets.

There was a nice youtube video if you have not seen it, but it seems to be gone now. :(

https://www.youtube.com/watch?v=HgE0T8EMaZk

I've got some pictures here, but they honestly don't add much value - you will know what to do reading the instructions.

http://www.rv8.ch/service-bulletin-sb-14-01-31/
 
That's the first thing I did after picking up a used kit. You'll need a 90° pneumatic drill to get to some of the rivets inside. I watched a YouTube video on how to do it afterward and they removed a bunch of top skin rivets to make access easier. If I were doing it again, I'd do the same.

If you opt not to do it, expect it to be a hot topic when selling. Not a must-have but you'll want to inspect often for cracks. If found, you'll have to do the SB.
 
SB-14-01-31

Haven't had the pleasure of encountering an RV requiring the service bulletin work being done, yet. Hope it stays that way.

The RVs I perform annuals on get thoroughly inspected (action items on my Annual Check Lists) each year and are documented that all SB inspections had been performed where applicable.
 
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SB

Haven't had the pleasure of encountering an RV requiring the service bulletin work being done, yet. Hope it stays that way.

The RVs I perform annuals on get thoroughly inspected (action items on my Annual Check Lists) each year and are documented that all SB inspections had been performed where applicable.

I'm in middle of incorporating the SB on my -8. I discovered the cracks during annual condition inspection several weeks ago. The air frame has 980 hours on it. I have inspected it every year since the SB came out.

I will say that you really need to take good quality picturess of the inspection area then zoom them in to see the cracks. I could not see the cracks when inspecting the area un-magnified with a mirror and bright light but when I saw the suspect areas in my pictures I looked again with a 10x loupe and it was clear that the cracks (1 on each side) were there. I wonder how often the cracks get missed when the area is inspected.

Skylor
 
I would highly encourage you to do this now. It will only be more difficult and more stressful in the future. I wouldn't hesitate to pull up some of the skins to get better access. Once the airplane is painted you may not feel you have that option. It's not a simple repair, so take your time on it. You'll sleep better when it's done.
 
Did it

I did the SB mod 15 months ago due to several smoking rivets on the bottom of the front spar think it took about 12 hours in the shop but I was replacing my VS & rudder ( due to the cracked .016 rudder skins ) anyway, now it’s painted and I sleep better at night
 
I did it more for my own piece of mind. It was a bit of work, but after so many years without doing real metal fabrication while doing the engine and panel, it was nice to get in there and drill out and drive some rivets.
Exactly this.

I dreaded the job going into it, but it really wasn’t that big of a deal to get it done. And for peace of mind, it’s priceless. Seriously, when it’s all done the forward spar looks stout like a bridge truss.

Since your horizontal stab is on the bench, this should be a no brainer to do the mod now, IMHO.
 
I'm in middle of incorporating the SB on my -8. I discovered the cracks during annual condition inspection several weeks ago. The air frame has 980 hours on it. I have inspected it every year since the SB came out.

I will say that you really need to take good quality picturess of the inspection area then zoom them in to see the cracks. I could not see the cracks when inspecting the area un-magnified with a mirror and bright light but when I saw the suspect areas in my pictures I looked again with a 10x loupe and it was clear that the cracks (1 on each side) were there. I wonder how often the cracks get missed when the area is inspected.

Skylor

;) Yeh, my flock of RV drivers are pretty sedate with their planes. I would assume you ask more of your airframe than this bunch!
Cheers
 
Thanks for the feedback. I wish that video was still available. I'm going to jump into the project this weekend and get it done. I just needed some motivation. I may try to video and take pictures to post my own youtube. It's a shame it wasn't done when originally constructed. Is Van's including this SB kit as part of the kits? It would make sense.

$
 
Pretty embarrassed to have to bring this up but as im reading this a light came on. I started my 7 this spring and as i was building the horizontal i read about antisplats spar doubler and i thought it was a good idea so i ordered it and installed it. Everything fit fine and looks great but now i see the doublers supplied by vans already did this. Sooooo i doubled my doublers. Is this junk now or do i have a super strong hs?
 
Pretty embarrassed to have to bring this up but as im reading this a light came on. I started my 7 this spring and as i was building the horizontal i read about antisplats spar doubler and i thought it was a good idea so i ordered it and installed it. Everything fit fine and looks great but now i see the doublers supplied by vans already did this. Sooooo i doubled my doublers. Is this junk now or do i have a super strong hs?

I have done very little research on this particular situation, however, combining 2 mods for the same thing is usually not a good idea. Even if it does make it stronger, adding strength to one place typically moves the stress point to another place eventually making the overall structure weaker.

Personally, I would remove the Antisplat doubler. Antisplat has some good products, but I don't really care for this particular one.
 
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Pretty embarrassed to have to bring this up but as im reading this a light came on. I started my 7 this spring and as i was building the horizontal i read about antisplats spar doubler and i thought it was a good idea so i ordered it and installed it. Everything fit fine and looks great but now i see the doublers supplied by vans already did this. Sooooo i doubled my doublers. Is this junk now or do i have a super strong hs?

Now I have someone to blame...........:D
 
I got the the antisplat doublers out and the easy rivets done but am struggling a bit with the rivets that go through the rib flange. I saw a picture where the builder used blind rivets for this. Is that an option?
 
I would think that the flanges should be doable with solid rivets, perhaps with an offset rivet-set (which you will need later if you don't have one) or even a squeezer. What's the specific difficulty with reaching them?
 
I got the the antisplat doublers out and the easy rivets done but am struggling a bit with the rivets that go through the rib flange. I saw a picture where the builder used blind rivets for this. Is that an option?

Fig 13 of the SB calls out allowable rivet substitutions.
 
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